Protists Protists Eukaryotes Not a monophyletic group Paraphyletic March 3 rd, 2011 Still use the term protist All eukaryotes except Plants, Fungi, Animals Most unicellular Some colonial Some multicelled Protist Body Plans Blurry lines separating these Different life stages can appear differently Protist Feeding Strategies Photoautotrophs Chloroplasts Heterotrophs Mixotrophs Can do photosynthesis and eat food Three feeding approaches have arisen independently multiple times Very diverse Use all three Protist Reproduction Other reproductive strategies that don t fit Endosymbiosis Mitochondria (proteobacteria) Chloroplasts (cyanobacteria) = plastids Secondary endosymbiosis One eukaryote phagocytized by another Evidence: Nucleomorph (vestigial nucleus) More membranes (up to 4) 1
Protist Systematics Kingdom Protista abandoned Some protists found to be fungi, plants, or animals 5 supergroups Present phylogeny is tentative, hypothetical, wrong A lot left to learn Linked by cytoskeletal morphology Some have excavated feeding groove Three Groups Diplomonads Parabasalids Euglenozoans Diplomonads Lack Plastids Modified Mitochondria (reduced) No electron transport chain Mostly anaerobic environments 2 equal size nuclei and multiple flagella Many are parasites Parabasalids Lack Plastids Modified Mitochondria (reduced) No electron transport chain H 2 gas released Mostly anaerobic environments Flagella Many are parasites Trichomonas vaginalis 2
Flagella have spiral or crystalline rod Predators, photosynthesis, parasites Kinetoplastids Euglenids Kinetoplastids Have single large mitochondrion Contains an organized mass of DNA Predators (prokaryotes) Parasites (eukaryotes) Trypanosoma Surface proteins change Euglenids Have one or two flagella Many mixotrophs Genetic Data suggests monophyly Secondary endosymbiosis of a red alga Controversial Some lack plastids and have no plastid genes Two main groups Alveolates and Stramenopiles Monophyly well supported Alveoli (membrane bound sacs) below plasma membrane Unknown function Dinoflagellates Apicocomplexans Parasites Ciliates Dinoflagellates Cellulose plates for reinforcement Two flagellain grooves Two flagella in grooves Spin Auto, hetero, mixotrophs Blooms Red tide (carotenoids) Toxins 3
Apicocomplexans Mostly parasites Apex contains complex for burrowing into hosts Retain modified plastid Complex life cycles Apicocomplexans Plasmodium causes malaria Ciliates Video Contain macronuclei and micronuclei Ciliates Marine algae Photoautotrophs and heterotrophs Hairy flagella Diatoms Unicellular Wall of SiO 2, overlap Most reproduction asexual Important marine and freshwater plankton May use diatoms to fight global warming 4
Golden Algae Yellow and brown carotenoids Biflagellate Photosynthetic, mixotrophic Most unicellular, some colonial Brown Algae Large (60m) and complex Multicellular Some specialized tissues Thallus Holdfast Stipe Blades Oomycetes Previously classified as fungi Hyphae Cellulose cell walls Chitin in fungi No plastids Decompose or parasitize Phytophthora Oomycetes Alternation of Generations Multicellular haploid and diploid stages Heteromorphic or isomorphic 5